Evidence of immunocyte stimulatory molecule(s) in plasma of patients undergoing cardiopulmonary bypass

Previous studies have demonstrated that cardiopulmonary bypass (CPB) induces a diffuse inflammatory response as well as cellular immunosuppression. To better characterize and localize this immune dysfunction, we examined the effect of CPB-exposed plasma on granulocytes and macrophages obtained from normal blood. Pre- and intra-CPB blood samples were obtained from seven patients admitted for elective coronary artery bypass graft surgery. Plasma from the preCPB samples served as controls. Evaluation of the behavior of the granulocytes and macrophages was based on their ability to respond by way of chemokinesis or chemotaxis versus a stimulus (D-Ala2-Met5-enkephalin [DAME], interleukin[IL]-1α). Non-CPB exposed granulocytes and macrophages were found to be capable of chemotaxis when stimulated by DAME and by IL-1α. Subjected to CPB, these cells were significantly more activated than controls (p < 0.005). They behaved in a chemokinetic fashion when incubated with cell-free CPB plasma and did not respond to either DAME or IL-1α in a chemotaxic situation when compared with controls (p < 0.005). Plasma subjected to CPB as stimulus provoked a chemotaxic response in non-CPB exposed cells. Taken together, these results indicate that at least one type of potent signal molecule was present, and possibly generated, in plasma subjected to CPB.